Sanitary washing devices are rapidly becoming popular, because they can make the human body clean by washing it with wash water.
In this context, a sanitary washing device is proposed including a pressure generating section for causing a pulsating transition in which a pressure higher than the water discharge pressure obtained from the supply water source is intermittently generated so as to achieve a comfortable washing feeling even with a reduced amount of water used (see Patent Document 1).
This sanitary washing device disclosed in Patent Document 1 can perform water discharge with increased velocity and repeatedly pulsating flow by causing the pulsating transition of pressure.
Thus, after discharge from the washing nozzle, discharged waters with different velocities unite into a large water drop, which can be caused to impinge on the human body. More specifically, a discharged water with a fast velocity overtakes a discharged water discharged earlier with a slow velocity to form a large water drop. Although discharged from the washing nozzle as a small water drop, a large water drop has been formed at the time of impingement on the human body. Thus, the disclosed technique is superior in being able to provide a comfortable washing feeling even with low supply flow rate.
However, the technique disclosed in Patent Document 1 has a problem in which there is a tradeoff between the “feeling of stimulation”, or the feeling of being strongly washed by wash water with a fast velocity, and the “feeling of volume”, or the feeling of being washed by a large amount of wash water. Specifically, to enlarge the water drop, which is formed using velocity difference between discharged waters, it is necessary to decrease the discharged water velocity to ensure overtaking of the subsequent discharged water. However, because of the slowdown in discharged water velocity, the “feeling of stimulation” decreases. Conversely, to enhance the “feeling of stimulation”, it is necessary to accelerate the discharged water velocity. However, if the discharged water velocity is accelerated, the previous discharged water cannot overtake the subsequent discharged water in a predetermined distance, failing to form a large water drop. Hence, the “feeling of volume” and the “feeling of stimulation” cannot be simultaneously achieved.
On the other hand, the inventors have investigated such techniques as in Patent Document 2 to realize a high washing feeling establishing compatibility between the feeling of volume and the feeling of stimulation.
Patent Document 2 discloses a sanitary washing device in which wash water is squirted straight from an orifice portion toward a water discharge port, passes through an air intake portion, and is discharged from the water discharge port (see claim 1, paragraphs 0006 to 0014, FIG. 2, etc. in Patent Document 2).
In this sanitary washing device disclosed in Patent Document 2, the surface of wash water is disturbed by the air taken in by the jet due to the air intake effect (ejector effect) to form a thin site and a thick site in the wash water. At the site where the wash water is thicker, in other words, where the wash water is denser, the discharged water causes the “feeling of volume” when impinging on the human body. Furthermore, because the wash water is squirted straight toward the water discharge port from the orifice portion for causing the ejector effect, it is possible to reduce energy loss due to collision of wash water with the nozzle inner wall surface, that is, to suppress the decrease in the “feeling of stimulation” due to deceleration of wash water. As compared with conventional sanitary washing devices, the technique is superior in being able to provide a high washing feeling establishing compatibility between the “feeling of volume” and the “feeling of stimulation”.
However, although this technique disclosed in Patent Document 2 can establish compatibility between the “feeling of stimulation” and the “feeling of volume” when the flow rate is relatively high, it cannot achieve the “feeling of stimulation” and provides an insufficient “feeling of volume” when the flow rate is relatively low. That is, the problem is that the “feeling of stimulation” and “feeling of volume” cannot be achieved at low flow rate. Furthermore, because of the configuration of creating the feeling of volume by generating disturbances in the surface of wash water by the ejector effect and creating the feeling of stimulation by suppressing the decrease in the velocity of wash water obtained by the supply water pressure, there is a limit to increasing the difference in feeling between the feeling of volume and the feeling of stimulation, and improvement is desired also from the viewpoint of providing a washing feeling at high level. Furthermore, because of the need of a device for causing the ejector effect, there is a problem with the size increase and cost of the device.
[Patent Citation 1]
JP 3264274
JP 2002-155567